This invention relates to compositions that can be used, for example, to clean, reduce the microbial population of, or sterilize surfaces, and to compositions that can be used for aseptic packaging.
There has been a longstanding need for antimicrobial agents having improved antimicrobial efficacy and improved speed of action. The specific requirements for such agents vary according to the intended application (e.g., sanitizer, disinfectant, sterilant, aseptic packaging treatment, etc.) and the applicable public health requirements. For example, as set out in Germicidal and Detergent Sanitizing Action of Disinfectants, Official Methods of Analysis of the Association of Official Analytical Chemists, paragraph 960.09 and applicable sections, 15th Edition, 1990 (EPA Guideline 91-2), a sanitizer should provide a 99.999% reduction (5-log order reduction) within 30 seconds at room temperature, 25xc2x12xc2x0 C., against several test organisms.
Many antimicrobial agents (e.g., iodophors, peracids, hypochlorites, chlorine dioxide, ozone, etc.) have a broad spectrum of antimicrobial properties. However, these agents sometimes have inadequate activity against bacterial spores, fungal spores, and fungi. Killing, inactivating, or otherwise reducing the active population of bacterial spores and fungi on surfaces is particularly difficult. Bacterial spores have a unique chemical composition of spore layers that make them more resistant than vegetative bacteria to the antimicrobial effects of chemical and physical agents. Likewise, the unique chemical composition of fungal cells, especially mold spores, makes them more resistant to chemical and physical agents than are other microorganisms. This resistance can be particularly troublesome when the spores or fungi are located on surfaces such as food, food contact sites, ware, hospitals and veterinary facilities, surgical implements, and hospital and surgical linens and garments.
Control of the mold Chaetomium funicola, and of bacterial spore-forming microorganisms of the Bacillus species, can be especially important during food packaging, particularly during cold or hot aseptic filling of food and beverage products. Microorganisms of the Bacillus species include Bacillus cereus, Bacillus mycoides, Bacillus subtilis, Bacillus anthracis, and Bacillus thuringiensis. These latter microorganisms share many phenotypical properties, have a high level of chromosomal sequence similarity, and are known enterotoxin producers. Bacillus cereus is one of the most problematic because Bacillus cereus has been identified as possessing increased resistance to germicidal chemicals used to decontaminate environmental surfaces. For example, Blakistone et al., Efficacy of Oxonia Active Against Selected Sporeformers, Journal of Food Protection, Volume 62, pp. 262-267, reported that Bacillus cereus was more tolerant to the effects of conventionally formulated peroxyacetic acid germicides than all other spore-forming bacteria tested, including other Bacillus and Clostridium species.
Bacillus cereus is frequently diagnosed as a cause of gastrointestinal disorders and has been suggested to be the cause of several food-borne illness outbreaks. Due to its rapid sporulating capacity, Bacillus cereus easily survives in the environment. Bacillus cereus is omnipresent in nature, and consequently can usually be found in animal feed and fodder. Bacillus cereus can contaminate raw milk via feces and soil, and can survive intestinal passage in cows and the pasteurization process.
Bacillus cereus is also known to cause serious human illness via environmental contamination. For example, Bacillus cereus is known to cause post-traumatic injury eye infections, which can result in visual impairment or loss of vision within 12-48 hours after infection. In addition, Bacillus cereus is regarded as transferable from washed surgical garments to patients.
Agents having greater or faster activity against bacterial spores, fungi, and other resistant microorganisms (particularly microorganisms of the Bacillus species) could help meet a substantial public health need, and one that is not adequately addressed by current commonly-used antimicrobial agents.
The present invention provides, in one aspect, a method for antimicrobial treatment comprising applying to microbes a composition containing a diluting solvent (e.g., water), an antimicrobially-active solvent having a density different from the density of the diluting solvent, and an optional cosolvent, surfactant, or additional antimicrobial agent, wherein the amount of antimicrobially-active solvent or additional antimicrobial agent is sufficiently high and the amount of cosolvent or surfactant is sufficiently low so that the composition will provide greater than a 1-log order reduction in the population of bacteria or spores of Bacillus cereus within 10 seconds at 60xc2x0 C. In a preferred aspect, the methods of the invention provide broader spectrum antimicrobial action, providing greater than a 1 -log order reduction within 10 seconds at 60xc2x0 C. in one or more additional organisms such as the mold Chaetomium funicola. In a more preferred aspect, the methods of the invention provide greater than a 1-log order reduction within 10 seconds at 60xc2x0 C. in Chaetomium funicola, Bacillus subtilis and Bacillus cereus. 
In another aspect, the invention provides a method for antimicrobial treatment, comprising applying to microbes a composition as described above, wherein the composition further comprises such additional antimicrobial agent. In a particularly preferred embodiment, the additional antimicrobial agent comprises a peracid such as peroxyacetic acid; a peroxide such as hydrogen peroxide; or a halogen containing compound such as hypochlorous acid (or its salts), chlorine dioxide, hypobromous acid (or its salts), or an interhalide such as iodine monochloride, iodine dichloride, iodine tetrachloride, bromine chloride, iodine monobromide, or iodine dibromide.
In yet another aspect, the invention provides an antimicrobial concentrate and instructions for mixing the concentrate with water, wherein the concentrate comprises an antimicrobially-active solvent that has a density different from that of water, an optional cosolvent or surfactant, and an optional additional antimicrobial agent, the amounts of antimicrobially-active solvent and optional additional antimicrobial agent being sufficiently high and the amount of cosolvent or surfactant being sufficiently low so that the composition will provide greater than a 1-log order reduction in the population of bacteria or spores of Bacillus cereus within 10 seconds at 60xc2x0 C. In a particularly preferred embodiment, the composition comprises said additional antimicrobial agent and the amount of antimicrobially-active solvent is sufficiently high and the amount of cosolvent or surfactant is sufficiently low so that the composition does not form a clear single-phase solution or microemulsion when the concentrate is mixed with water according to the instructions.
In a further aspect, the invention provides an antimicrobial composition comprising a diluting solvent, an antimicrobially-active solvent having a density that is different from the density of the diluting solvent, an additional antimicrobial agent, and an optional cosolvent or surfactant, the amounts of antimicrobially-active solvent and of additional antimicrobial agent being sufficiently high and the amount of cosolvent or surfactant being sufficiently low so that the composition will provide greater than a 1-log order reduction in the population of bacteria or spores of Bacillus cereus or the mold Chaetomium funicola within 10 seconds at 60xc2x0 C.
In yet another aspect, the invention provides an antimicrobial concentrate and instructions for mixing the concentrate with water, wherein the concentrate comprises an antimicrobially-active solvent that has a density different from that of water, an optional cosolvent or surfactant, and an additional antimicrobial agent, the amounts of antimicrobially-active solvent and additional antimicrobial agent being sufficiently high so that the composition will provide greater than a 1-log order reduction in the population of bacteria or spores of Bacillus cereus or the mold Chaetomium funicola within 10 seconds at 60xc2x0 C. In a particularly preferred embodiment, the composition comprises a sufficiently high amount of additional antimicrobial agent and antimicrobially-active solvent such that the composition forms a clear single-phase solution when the concentrate is mixed with water according to the instructions, and provides greater than a 1-log order reduction in the population of bacteria or spores of Bacillus cereus or Bacillus subtilis and in the population of the mold Chaetomium funicola within 10 seconds at 60xc2x0 C.
The method and compositions of the invention are especially useful for aseptic packaging, re-use clean-in-place (CIP) or clean-out-of-place (COP) systems, hospital disinfectants, veterinary clinic disinfectants, and as sporicides or sterilants.